The invention is based on a pivotal robot arm comprising plural basic bodies. The basic bodies include a support body, at least one pivot arm and a working device. The at least one pivot arm has first and second extreme ends and parallel articulation axes. A pivot arm is articulated to the support body at a first end, and a pivot arm is articulated to the working device at a second end. Prior art pivotal robot arms of this type include housing components constructed of cast structures or welded composite structures of sheet metal or semi-finished castings. The cast or welded structures require a lot of material and high processing expenditures. EP-B1 0,265,835 discloses a pivot arm configuration for an industrial robot composed of two identical, extruded individual elements that have the length of the arm. Here the hollow shape extends in the direction of the reach of the pivot arm so that additional bearing points must be introduced into the pivot arm for the pivot axes.